Base wad overlay



March 7, 1961 H. E. CLARK, JR 2,973,711

BASE WAD OVERLAY Filed Feb. 4. 1959 FIG 6 41 INVENTOR.

' HOMER E. CLARK. JR.

ATTORNEY Patented Mar. 7, l fil BASE WAD OVERLAY Homer E. Clark, In, Alton, IlL, assignor to Alcan Company, Incorporated, Foster Township, 111., a corporation of Illinois Filed Feb. 4, 1959, Ser. No. 791,079

4 Claims. (Cl. 102-42) This invention relates in general to shotgun cartridges and, more particularly, to certain new and useful improve ments in base wad overlays therefor.

In shotgun cartridges it is of critical importance that there be maximum confinement of the gases of explosion so that the force thereof acting upon the shot charge will be undirninished by gas leakage and thereby conduce to development of desired breach pressure and muzzle velocity without distortion of the head portion of the shell. Base wads have been generally used in an effort to seal the headed end of the cartridges against gas leakage, as well as for the purpose of integrating the head structure of the cartridge, but base wads have not proved consistently effective against gas loss and head distortion. One of the primary reasons for this generally accepted, unsatisfactory condition is that a gas-tight seal is not produced between the base wad and the primer so that upon ignition of the charge gas will leak outwardly about the primer and into the flange portion of the cartridge head, as well as against the central portion of the head. The blockage of the space surrounding the primer has not been hertofore achieved in a reliable, consistent manner.

Furthermore, in many base wad constructions, the lack of a snug reception of the same within the head portion of the cartridge is productive of a shearing action about the upper edge of the head since the wall of the paper tubular body immediately thereabove will normally be bulged radially outwardly, under force of gases leaking about the base wad, and over such edge which thus serves as a shear or cutter.

Therefore, in view of the foregoing, it is an object of the present invention to provide a base wad overlay for snug, superimposed disposition upon a base wad and adapted to be wedgingly received about the primer so that gas leakage is prevented at the headed end of a shotgun carridge.

It is a further object of the present invention to provide a base wad overlay for covering relationship upon a base wad, shielding same against immediate action thereon by the gases of explosion for obviating undesired distortion or destruction thereof with consequent gas leakage therethrough or thereabout.

It is an additional ob ect of the present invention to provide a base wad overlay designed for positive engagement with the associated base wad to prevent any prema ture or accidental relative displacement.

It is a still further object of the present invention to provide a base wad overlay which may be manufactured most economically; the incorporation of which during cartridge assembly may be most easily and simply effected, and being amenable to such incorporation either during assembly prior to final heading or within the empty shell subsequent to primer positionment; and which is reliable in usage for achieving gas confinement not hitherto at tainable.

Other objects and details of the invention will be apparent from the following description, when read in connection with the accompanying drawing (1 sheet) wherein:

Figure l is a longitudinal sectional view of a shotgun cartridge embodying a base wad overlay constructed in accordance with and embodying the present invention.

Figure 2 is a perspective, partially broken away, view of the base wad overlay.

Figure 3 is a top plan view of the base wad overlay illustrated in Figure 2.

Figure 4 is a partial, longitudinal sectional view of a shotgun cartridge incorporating another form of base wad overlay constructed in accordance with and embodying the present invention.

Figure 5 is a perspective view of the base wad overlay shown in Figure 4.

Figure 6 is a fragmentary longitudinal sectional view of a shotgun cartridge embodying another form of base wad overlay constructed in accordance with and embodying the present invention, showing the cartridge prior to heading and insertion of the primer.

Figure 7 is a perspective view, partially broken away, of the base wad overlay illustrated in Figure 6.

Figure 8 is a fragmentary longitudinal sectional view of a shotgun cartridge incorporating the base wad overlay illustrated in Figure 6, showing the primer in position.

I Referring now by reference characters to the drawing which illustrates practical embodiments of the present invention, A designates a shot shell or shotgun cartridge comprising a tubular body or casing l, as of metal, paper, or the like, there being a conventional metallic head 2 mounted upon one end of said body 1 and having the customary base flange 3 and being centrally apertured, as at 4, to receive a primer 5. Within body 1 concentric with and disposed encirclingly about primer 5 is a base wad 6 which is surmounted by a base wad overlay 7 above which latter there is presented a propellant charge 8.

Superimposed on charge 8 is an obturating wad 9, which may, if desired, be of the construction shown in my copending application filed December 4, 1958, Serial No. 778,093, while thereabove is disposed conventional filler or separator wads 10, 11. Provided upwardly of said wads 10, 11 is the shot charge 12, preferably of multirnissile character, while the upper end of shell A is closed in any customary manner, as, for example, by the infolding of body 1.

Base wad 6 may be fabricated of any suitable material, such as pulp and the like, and is dimensioned for close fitting reception within the lower end of body 1 for producing a strong base structure. Said base wad 6 is provided with a central axial bore 13 within the lower portion of which primer 5 is received so that wad 6 is in circumambient relation thereto. The upper portion of bore 13 flares outwardly, as at 14, with the extreme upper end edge of wad 6 defining a lip-like structure, as at 15, which is in tight surface-abutting relationship with the inner face of the Wall of body It. Ease wad overlay 7 is of general, funnel shape and being hence of a configuration basically complementary to the flaring or sloping character of bore 13 of wad 6, and is preferably of molded plastic construction. The tapering or increasingly restricted portion 16 of base wad overlay '7 terminates in a tubular cylindrical base 16' having relatively thickened wall portions the upwardly directed face 17 of which defines a tool-receiving surface for purposes presently appearing, will be inserted within bore 13 and wedgingly driven into the space immediately surrounding primer 5, thereby causing compression of wad 6 through the radially outward force developed by jamming of overlay 7 into such position. Accordingly, base wad 6 will be encased by the combination of overlay 7, body 1 and head 2, whereby no portion thereof will be immediately exposed to the gases of explosion upon ignition of charge 8 so that the same is thus protected against heat as Well as gas leakage therethrough.

The base 16' of overlay 7 being disposed tightly encircling about primer 5 will completely seal the customary spacing between same and base wad 6 and thereby effect the creation of a gas seal in a region .whichhas heretofore been only partially rendered gas-proof.

Base 16 is provided with a circumferentially extending upwardly and inwardly, tapering trough or recess, as at 18 in its inner portion so that limited flexibility will be accorded the primer-engaging Zone for assuring a snug, tight fit thereabout. At its upper end overlay 7 will snugly abut on its upper side portions, immediately above wad 6, the inner face of body 1 so that no gas leakage will be developed therebetween. Thus, overlay 7 defines a rearward portion of the propellant charge compartment and, hence, upon ignition, confines the explosion so that maximum gas pressure will be available for propelling the shot charge with prevention of diminution of such pressure by gas leakage through the base wad or about the primer and thence into flange 3 whereby optimum breach pressure and muzzle velocity will be effected.

With reference to Figure 1, it will be seen that the upper end portion of base wad overlay 7 will be disposed spacedly above the upper end edge of head 2. This a most important feature since it prevents the development of a shearing action upon explosion of the propellant gases. If the upper edge of base wad overlay 7 was aligned with the upper edge of head 2, the latter, upon explosion, would serve as a cutting edge whereby the cartridge casing would be cut therealong with consequent gas loss.

Overlay 7 is fabricated, of desirably molded plastic, and can be fixed into the empty primed shell, that being wherein the primer 5 and base wad 6 have already been installed, by means of a plunger-type tool operating against surface 17, which tool will drive said overlay 7 downwardly base wad 6 with a portion wedging between primer 5 and over base wad 6 whereby reliable, mutual, frictional engagement will be brought about between said wad 6, overlay 7 and primer 5. The upper end portion of overlay 7 may normally be of a diameter slightly in excess of the inside diameter of body 1 so that under action of the positioning plunger the edges of such upper end portion will be forced contractingly inwardly for seal-forming relationship with the inner face of body 1.

It is to be particularly noted that the diamteer of the opening through base 16' of overlay 7 will normally be slightly less than the outside diameter of the primer 5 to be received therein so that upon mutual engagement of the same, the inner portion of the base 16 will be driven radially outwardly. The relatively thin-walled character of this inner portion of base 16' thus permits of this necessary expansion which assures the tight seal requisite. If desired, base wad overlay 7 may be maintained in position prior to insertion of primer 5, which latter may then be driven into fixed position, effecting sealing relation with base wad overlay 7.

Referring now to Figures 4 and 5, another form of base wad overlay, indicated at 27, is disclosed, which is constructed in accordance with the present invention. Said overlay 27 being preferably fabricated of a suitable plastic material, and hence fully preformed, is of general, inverted conical or funnel form, similar to overlay 7 hereinabove described, and being provided with a circumferentially recessed, base 28. On the outer face of said base 28 there is provided a plurality of spaced apart, circumferential bead-like projections or protuberances 29 for limited penetrating extension into the adjacent, surrounding portion of the associated base wad indicated at 30 in Figure 4 so that a positive locking engagement is effected therebetween whereby inadvertent displacement of said overlay 27 is inhibited.

In assembly, overlay 27 is driven into the empty primed shell by a suitable plunger or related type tool so that the lower end thereof is in desired, close-fitting, encircling relationship to primer 5 for sealing of the zone immediately surrounding said primer, with projections 29 being forced within the base wad 3t) so that a secure, fully integrated base construction is provided the cartridge.

Referring to Figures 6, 7 and 8, another form of base wad overlay, indicated 37, is disclosed, which is constructed in accordance with the present invention. Said overlay 37, being preferably fabricated of a suitable metal and fully preformed, is of general cup-formation having an upper wall portion 38, a base wall 39 having a central aperture 41 from the edge of which depends a plurality of fin-like members 41 to define a sleeve for embracingly receiving a primer 42. Said fin-like members 41 are turned slightly outwardly at theirlower ends, as at 43, to provide an enlarged mouth to facilitate entry of primer 42. Overlay 37 may be fixed into the empty shell during normal assembly thereof and before formal heading and priming, as suggested in Figure 6. In this method of fixing overlay 37 into position a metal punch in the heading operation replaces the primer in such a way so that upon compression of the base wad, as indicated at 44, the same is forced against the lower ends of fin-like members 41 of overlay 37. The diameter of the fin-defining sleeve is slightly less than the outside diameter of primer 42 so that when the same is forced into the empty shell, overlay 37 will be wedged between base wad 44 and primer 42, as illustrated in Figure 8, whereby a positive locking engagement is effected therebetween to avoid inadvertent displacement of overlay 37 and to further provide a secure and fully integrated base construction for the cartridge.

It should be understood that changes and modifications in the form, construction, arrangement, and combination of the several parts of the base wad overlay may be made and substituted for those herein shown and described without departing from the nature and principle of the present invention.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. In a shotgun cartridge having a primer and a base wad surrounding said primer, a base wad overlay of molded thermoplastic construction for wedging, gasscaling disposition between the primer and the base wad comprising a generally funnel-shaped body for disposition upon said base wad, there being a cylindrical base portion in the narrow end of said body having an opening therethrough for engaging said primer throughout a portion of its length and for disposition between the same and the base wad, said base portion having an upwardly opening recess at its upper end in radially spaced relationship to the opening, being concentric with said opening and forming a lip portion for engagement with said primer so that a relatively thin, limitedly expansible wall portion intervenes between the said recess and the opening.

2. A base wad overlay as described in claim 1 wherein spaced apart head like protuberances are provided on the outer surface of the base portion for projection into the adjacent portions of the base wad.

3. In a shotgun cartridge having a primer and a base wad surrounding said primer, a base wad overlay of molded thermoplastic construction for Wedging, gassealing disposition between the primer and the base wad comprising a generally funnel-shaped body for disposition upon the .base wad and having a cylindrical base portion at the narrow end of said body provided with. an opening therethrough for snugly receiving the primer throughout a substantial portion of its length and for wedging disposition between same and the base wad, there being a recess provided in the upper surface of the cylindrical base portion of said body disposed radially outwardly of, and in con centricity with, the opening and being of upwardly increasing, cross-sectional extent being of general V-shape in section, said recess being rel": tively nearer the primer than the outer portion of said a substantial portion of its length, the wall of said bore being normally of less diameter than the diameter of the primer for assuring snug, abutting contact on its inner surface for the outer surface of the primer, said cylindrical portion being provided with an annular cut-away portion in its upper surface to define an inner primerengaging wall portion of limited expansibility.

References Cited in the file of this patent UNITED STATES PATENTS 450,454 Gardner Apr. 14, 1891 1,006,828 Clyne Oct. 24, 1911 1,842,445 Clyne Jan. 26, 1932 FOREIGN PATENTS 547,721 Italy Sept. 14, 1956 1,128,191 France Oct. 20, 1956 

